It is, of course, customary for trained personnel such as masseurs, athletic trainers and chiropractors to massage the spinal areas and selected back portions of a client, player or patient. Although there are different manual techniques which are still employed, various massage machines have been developed for repetitively flexing the back muscles on each side of the spinal column of a person lying in a supine position. A typical one of these machines is seen in U.S. Pat. No. 2,175,614 which machine includes a plurality of horizontal transversely-oriented rollers that are respectively supported by upright coil springs that are arranged along each side of a carriage which is movably mounted on parallel horizontal tracks. To operate the machine, the carriage is moved back and forth along its tracks so that the rollers will massage the back of a person lying face-up on a hammock suspended just above the rollers.
U.S. Pat. No. 2,577,646 discloses a similar massaging machine having a horizontal table that is appropriately sized to accommodate a person lying face up on the table with his spine centered over an elongated longitudinal opening in the central portion of the table. A plurality of transversely-oriented rollers are respectively journalled to the edges of paralleled endless belts that are cooperatively arranged just below the surface of the table on each side of the opening. By driving the belts in unison, the rollers are successively moved along the length of the elongated opening so as to impart a rolling action to the spinal region of the person lying on the table. U.S. Pat. No. 4,011,862 shows a similar massaging machine which instead has two sets of transverse rollers that have their outer ends slightly elevated in relation to their respective inner ends which define an upwardly-facing concavity for partially cradling the back of a person as the rollers are moved in unison along each side of the spinal column of that person.
Other prior-art machines have been arranged to impart upward and downward movements to a single transversely-oriented massaging member for achieving a desired massaging action. For instance, the machine disclosed in U.S. Pat. No. 1,638,025 has a matched pair of elongated, sinusoidal bars that are operatively journalled at their ends to a suitable frame so that the bars can be respectively rotated about paralleled longitudinal axes. The curved portions of the sinusoidal bars are transversly aligned and the ends of a plurality of closely-spaced transverse slats are loosely coupled to the curved bars so as to support a person midway between the bars. In this manner, as the bars rotate in unison, the slats will remain horizontal as they move upwardly and downwardly for imparting a combined rocking and undulating motion to the back of a person lying on the slats.
On the other hand, U.S. Pat. No. 3,628,528 shows a machine with a single horizontal roller which is mounted on a carriage that can be moved as required to selectively position the roller below a particular body portion that is considered to require concentrated massaging action. The roller is journalled between two vertically-movable members that are reciprocated in unison by a pair of cranks which are mounted in an out-of-phase relationship on opposite ends of a motor shaft so that rotation of the motor shaft will rock the roller in a vertical plane as its ends are alternately moved upwardly and downwardly by the two members.
It is apparent, however, that neither the machines seen in the aforementioned patents nor those massaging machines which are known to be in use today are capable of imparting independent but coordinated massaging actions to two or more portions on the back of a person. Intead, the machines shown in these several prior-art patents as well as the present-day machines all seem to be directed toward providing only a single type of massaging action. Moreover, from these patents it is readily apparent that heretofore no attempt has been made to impart one type of massaging action to the spinal column itself as a different type of massaging action is simultaneously being imparted to those portions of the back that are disposed along opposite sides of the spinal column.